Q. How much fluid should I drink before training and when? Also how much fluid should I drink while I am training and what should I drink water, powerade etc? And do you know two ways to determine my own hydration level? Will water alone be enough for players to compete at their best and allow full recovery?
A. The USTA Sport Science Committee has put together fluid replacement guidelines and this information is available on the High Performance website.
In general, you want to:
Top off your fluid stores by drinking 12-16 oz of fluid 1 hour prior to competition.
Drink 4-8 swallows of fluid after your warm-up and on EVERY changeover during play.
Drink 20-24 oz of fluid for every pound of body weight lost during play to replenish the body's fluid stores.
Whether to use water or a sports drink is something you have to determine on your own. The three things you should be replacing during or after play are fluids, energy/ carbohydrates, and electrolytes.
Many sports drinks contain all of these, but you can also obtain these through a combination of drinking water and eating appropriate snacks. Some people have difficulties with sports drinks, so the later suggestion may be for you if drinks like Gatorade or Powerade are hard on your stomach.
Two simple ways you can determine your hydration status are:
1. Monitor the color of your urine. In a well-hydrated person, urine will be very light to clear - the color of straw. Darker, more concentrated urine is an indicator that you are dehydrated.
2. Weigh yourself before and after play. Any weight loss you experience during play is due to fluid loss and that weight should be replaced before the next practice or match. Make sure when weighing yourself, however, that you wear similar DRY clothes, and not the sweaty clothes you came off the court in.
Q. I am a recreational tennis player trying to lose a few pounds through exercise and good nutrition. What is your opinion of maltodextrin in protein shakes? Some manufacturers rag on it while most use it.
A. I am not sure of the maltodextrin controversy referenced in the question, but maltodextrin is a carbohydrate-like substance that comes from splitting corn syrup. Corn syrup is similar to table sugar and is used in a variety of products for its sweet taste.
Maltodextrin is sometimes listed as a “modified starch” and like tapioca and rice starch is used in food products to provide stability and texture, to mimic fat without the fat calories. There are no established ill effects of consuming reasonably amounts of maltodextrin in foods.
As with any natural substance, substances derived from natural sources, or man made substances, however, balance is the key.
Q. It is apparent that the professionals on tour do not ingest the typical sports drinks that are used in mainstream America. Their drinks have a different color and there are other visual indicators that indicate they are not Gatorade, etc. (labels are always absent when they are drinking these "mystery" beverages). Do you have any insight into what kind of mixtures they are using?
A. Actually, many of the players (especially on the women’s tour) drink exactly what many Americans drink - Gatorade® and water.
Some of the European sports drinks that are also used are very similar to Gatorade® in nutrient content. One such drink on the men’s side is Lucozade™. Some players are also using Cytomax™; though this is not as popular as it once was.
Q. Is it possible to drink too much liquid during a match? I drank over 66 ounces of water and 10 ounces of Gatorade and I was still thirsty. During the day, I drank way over my limit too (over 100 ounces)! I am a 130 pound woman in good physical shape, but I seem to drink more than everyone else and wonder why.
A. Yes; it is possible to drink to much fluid during play and off the court. However, without knowing your sweat rate during that match, your hydration status before your began play (You may have started the match significantly dehydrated.), and the length of the match, it’s difficult to assess whether or not the fluid consumption that you described was appropriate.
Some adults can tolerate (and should consume, based on their sweat rate) up to 2 liters (about 70 ounces) of fluid per hour during play. Again, if you sweat a lot and the match lasts 2 hours, then 76 ounces of total fluid consumption might not even be enough! If you feel the need to drink that much, you likely need it.
Now, on the other hand, if you are over-consuming fluid (particularly low- or no-sodium fluid) over a relatively short period of time (on the court or off), at the least, you’ll likely have to go to the bathroom more than usual. More seriously, you could induce a certain level of hyponatremia (low blood sodium) that could lead to problems ranging from poor performance to seizures or even worse. Notably, some women may be more at risk for fluid overload and hyponatremia due to their size and, at times, contributing effects of estrogen.